/*
 * Copyright 1997-2003 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package org.loon.framework.android.game.core.graphics.geom;

import java.util.*;

/**
 * A utility class to iterate over the path segments of an ellipse through the
 * PathIterator interface.
 * 
 * @author Jim Graham
 */
class EllipseIterator implements PathIterator {
	double x, y, w, h;
	AffineTransform affine;
	int index;

	EllipseIterator(Ellipse2D e, AffineTransform at) {
		this.x = e.getX();
		this.y = e.getY();
		this.w = e.getWidth();
		this.h = e.getHeight();
		this.affine = at;
		if (w < 0 || h < 0) {
			index = 6;
		}
	}

	/**
	 * Return the winding rule for determining the insideness of the path.
	 * 
	 * @see #WIND_EVEN_ODD
	 * @see #WIND_NON_ZERO
	 */
	public int getWindingRule() {
		return WIND_NON_ZERO;
	}

	/**
	 * Tests if there are more points to read.
	 * 
	 * @return true if there are more points to read
	 */
	public boolean isDone() {
		return index > 5;
	}

	/**
	 * Moves the iterator to the next segment of the path forwards along the
	 * primary direction of traversal as long as there are more points in that
	 * direction.
	 */
	public void next() {
		index++;
	}

	// ArcIterator.btan(Math.PI/2)
	public static final double CtrlVal = 0.5522847498307933;

	/*
	 * ctrlpts contains the control points for a set of 4 cubic bezier curves
	 * that approximate a circle of radius 0.5 centered at 0.5, 0.5
	 */
	private static final double pcv = 0.5 + CtrlVal * 0.5;
	private static final double ncv = 0.5 - CtrlVal * 0.5;
	private static double ctrlpts[][] = { { 1.0, pcv, pcv, 1.0, 0.5, 1.0 },
			{ ncv, 1.0, 0.0, pcv, 0.0, 0.5 }, { 0.0, ncv, ncv, 0.0, 0.5, 0.0 },
			{ pcv, 0.0, 1.0, ncv, 1.0, 0.5 } };

	/**
	 * Returns the coordinates and type of the current path segment in the
	 * iteration. The return value is the path segment type: SEG_MOVETO,
	 * SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, or SEG_CLOSE. A float array of
	 * length 6 must be passed in and may be used to store the coordinates of
	 * the point(s). Each point is stored as a pair of float x,y coordinates.
	 * SEG_MOVETO and SEG_LINETO types will return one point, SEG_QUADTO will
	 * return two points, SEG_CUBICTO will return 3 points and SEG_CLOSE will
	 * not return any points.
	 * 
	 * @see #SEG_MOVETO
	 * @see #SEG_LINETO
	 * @see #SEG_QUADTO
	 * @see #SEG_CUBICTO
	 * @see #SEG_CLOSE
	 */
	public int currentSegment(float[] coords) {
		if (isDone()) {
			throw new NoSuchElementException("ellipse iterator out of bounds");
		}
		if (index == 5) {
			return SEG_CLOSE;
		}
		if (index == 0) {
			double ctrls[] = ctrlpts[3];
			coords[0] = (float) (x + ctrls[4] * w);
			coords[1] = (float) (y + ctrls[5] * h);
			if (affine != null) {
				affine.transform(coords, 0, coords, 0, 1);
			}
			return SEG_MOVETO;
		}
		double ctrls[] = ctrlpts[index - 1];
		coords[0] = (float) (x + ctrls[0] * w);
		coords[1] = (float) (y + ctrls[1] * h);
		coords[2] = (float) (x + ctrls[2] * w);
		coords[3] = (float) (y + ctrls[3] * h);
		coords[4] = (float) (x + ctrls[4] * w);
		coords[5] = (float) (y + ctrls[5] * h);
		if (affine != null) {
			affine.transform(coords, 0, coords, 0, 3);
		}
		return SEG_CUBICTO;
	}

	/**
	 * Returns the coordinates and type of the current path segment in the
	 * iteration. The return value is the path segment type: SEG_MOVETO,
	 * SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, or SEG_CLOSE. A double array of
	 * length 6 must be passed in and may be used to store the coordinates of
	 * the point(s). Each point is stored as a pair of double x,y coordinates.
	 * SEG_MOVETO and SEG_LINETO types will return one point, SEG_QUADTO will
	 * return two points, SEG_CUBICTO will return 3 points and SEG_CLOSE will
	 * not return any points.
	 * 
	 * @see #SEG_MOVETO
	 * @see #SEG_LINETO
	 * @see #SEG_QUADTO
	 * @see #SEG_CUBICTO
	 * @see #SEG_CLOSE
	 */
	public int currentSegment(double[] coords) {
		if (isDone()) {
			throw new NoSuchElementException("ellipse iterator out of bounds");
		}
		if (index == 5) {
			return SEG_CLOSE;
		}
		if (index == 0) {
			double ctrls[] = ctrlpts[3];
			coords[0] = x + ctrls[4] * w;
			coords[1] = y + ctrls[5] * h;
			if (affine != null) {
				affine.transform(coords, 0, coords, 0, 1);
			}
			return SEG_MOVETO;
		}
		double ctrls[] = ctrlpts[index - 1];
		coords[0] = x + ctrls[0] * w;
		coords[1] = y + ctrls[1] * h;
		coords[2] = x + ctrls[2] * w;
		coords[3] = y + ctrls[3] * h;
		coords[4] = x + ctrls[4] * w;
		coords[5] = y + ctrls[5] * h;
		if (affine != null) {
			affine.transform(coords, 0, coords, 0, 3);
		}
		return SEG_CUBICTO;
	}
}
